Minimally invasive surgery is commonly performed by inserting relatively small instruments into the body, as well as organs within the body, through one or more very small incisions. Many instruments are rigid and are directed to a site of interest by angling the instrument through the incision and inserting the device to a selected depth within the body. However, rigid instruments are unacceptable for many procedures, and even less invasive procedures have been developed that employ flexible catheter-based instruments. Although early catheter devices simply followed the contours of a body passage, such as a blood vessel to a selected treatment site, catheters with movable tip portions were developed to provide simple catheter steering.
The present steerable catheters most commonly include one or more wires that are anchored at a first point near the distal tip of the catheter and at a second point at the proximal end of the catheter or in a handle unit. A lever or knob is actuated to apply or reduce tension on the one or more wires causing the distal tip of the catheter to be pulled in the direction of the tension. Although steering mechanisms such as these have provided excellent results, it is believed that even greater steering or deflection control would further increase the possibilities for new surgical procedures. It would be especially desirable if existing and well developed pull-wire technology could be employed with new structures to provide such enhanced capability.